This invention relates to a method of eliminating transient in an apparatus comprising a current source and several functional blocks, at least one of which consumes a pulsating current which produces transients in the operating voltage.
In apparatuses in which the consumption of current by different blocks varies greatly and in which the consumption of current may be pulse-like, transients are formed in the operating voltage. When included in the operating voltage, transients are detrimental to those functional blocks which require a very stable operating voltage to function properly. For example, an especially stable operating voltage is required in digital radio telephones having a digital system based on time division multiplexing (TDMA). In this system, voltage-controlled oscillators (VCO) are used, for example, in the SAT detector and also in other blocks. As a result any transients in the supply voltage will cause great frequency deviations in the various circuits. Therefore, very strict specifications have been set for voltages in the TDMA system.
Usually transients are eliminated by means of various filters or a voltage regulator. When a transient is very sharp, a conventional regulator is not capable of following it and, thus, the transient is seen in the regulator output as a greater-than-allowed voltage variation. It is, therefore, difficult to eliminate transients completely by known methods.